p-Block Elements
13th to 18th Group
, Group 13 Elements- Boron Family
Physical Properties
Boron (B) Aluminium (Al) Gallium (Ga) Indium (In) Thallium (Tl)
Atomic No. 5 13 31 49 81
Configurati [He]2s22p1 [Ne]3s23p1 [Ar]4s23d104p1 [Kr]5s24d105p1 [Xe]6s25d106p1
on
Atomic 85 143 135 167 170
Radius pm)
IE (kJ/mol) 801 577 579 558 589
Density 2.35 2.7 5.9 7.31 11.85
(g/ml)
MP (K) 2453 933 303 430 576
BP (K) 3923 2740 2676 2353 1730
E.N 2.0 1.5 1.6 1.7 1.8
, Chemical Properties
• Due to very high IE boron doesn’t form B3+, it only
forms covalent compounds.
• Tendency to show +3 state decreases down the
group due to “inert pair” effect. The stability of +1
state increases down the group.
• AlX3 are covalent compounds and exist as dimer in
vapor state and in non polar solvents but in polar
solvents they dissolve to form [Al(H2O)6]3+ and 3X-
ions.
, • Reactions of Boron-
• Pure crystalline boron is very unreactive but amorphous boron shows
many reactions.
Reaction Comment
B(red hot) + H2O (steam) B2O3 + H2 Water or steam don’t affect boron
4B +3O2 2B2O3 At High temperature
2B + N2 2BN At very high temperature
2B + 3X2 2BX3 (X=F,Cl,Br,I) At high temperature
2B + 6NaOH 2Na3BO3 + 3H2 When fused with alkali
2B + 2NH3 2BN + 3H2 At very high temperature
yB + xM MxBy Many metals form borides (not
group-1)
Eg- Mg3B2, Ca3B2, B4C, CrB2 etc
2B + 3H2SO4 (hot & conc) 2H3BO3+ SO2
2B + 6HNO3 (hot & conc) 2H3BO3 + NO2
13th to 18th Group
, Group 13 Elements- Boron Family
Physical Properties
Boron (B) Aluminium (Al) Gallium (Ga) Indium (In) Thallium (Tl)
Atomic No. 5 13 31 49 81
Configurati [He]2s22p1 [Ne]3s23p1 [Ar]4s23d104p1 [Kr]5s24d105p1 [Xe]6s25d106p1
on
Atomic 85 143 135 167 170
Radius pm)
IE (kJ/mol) 801 577 579 558 589
Density 2.35 2.7 5.9 7.31 11.85
(g/ml)
MP (K) 2453 933 303 430 576
BP (K) 3923 2740 2676 2353 1730
E.N 2.0 1.5 1.6 1.7 1.8
, Chemical Properties
• Due to very high IE boron doesn’t form B3+, it only
forms covalent compounds.
• Tendency to show +3 state decreases down the
group due to “inert pair” effect. The stability of +1
state increases down the group.
• AlX3 are covalent compounds and exist as dimer in
vapor state and in non polar solvents but in polar
solvents they dissolve to form [Al(H2O)6]3+ and 3X-
ions.
, • Reactions of Boron-
• Pure crystalline boron is very unreactive but amorphous boron shows
many reactions.
Reaction Comment
B(red hot) + H2O (steam) B2O3 + H2 Water or steam don’t affect boron
4B +3O2 2B2O3 At High temperature
2B + N2 2BN At very high temperature
2B + 3X2 2BX3 (X=F,Cl,Br,I) At high temperature
2B + 6NaOH 2Na3BO3 + 3H2 When fused with alkali
2B + 2NH3 2BN + 3H2 At very high temperature
yB + xM MxBy Many metals form borides (not
group-1)
Eg- Mg3B2, Ca3B2, B4C, CrB2 etc
2B + 3H2SO4 (hot & conc) 2H3BO3+ SO2
2B + 6HNO3 (hot & conc) 2H3BO3 + NO2
